The present specification is directed to systems, apparatus and methods for prophylactically preventing, or for treating the onset and/or progression of Cerebral Amyloid Angiopathy (CAA), acute stroke conditions, or Alzheimer's disease. The progression of, stabilizing, or improving symptoms related to these conditions are treated by monitoring a pathophysiological change indicative of the conditions in a patient, based on the monitoring, determining if amyloid plaque is present in a perivascular space of the patient, optionally determining an extent of amyloid plaque in the perivascular space, and based on the presence of amyloid plaque in the perivascular space of the patient, determining a treatment protocol for the patient. The treatment protocol includes administering to the patient a high density lipoprotein composition derived from mixing a blood fraction with a lipid removing agent.
